Below is a lists of the organisations that have attracted a considerable amount of complaints from consumers who have came into contact with them:

Resort Condominium International (RCI) - session is held at one of the shopping malls beside Thai Embassy
WorldVentures - personal experience tells me that they will arrange for meetup at CityHall - Raffles City Shopping Centre Macdonalds to precise.

This post will be updated along the way when more information are gathered.